1. Field of the Invention (Technical Field)
The present invention relates to motorcycles, particularly to an off-road competition motorcycle comprising an internal combustion engine having at least one cylinder, and a front wheel as well as a rear wheel, a tubular trellis frame and a self-supporting fuel tank configured as a rear tank mounted at the rear end of the off-road competition motorcycle, releasably secured to the tubular trellis frame.
2. Background Art
Motorcycles, quite generally, and also those intended for biking cross-country, in other words off-road competition motorcycles, normally feature a fuel tank disposed between the handlebars and the biker when seated on the motorcycle. Such a fuel tank is usually termed saddle tank, because it features side tanks downswept about the frame of the motorcycle like the flaps of a saddle to provide a corresponding amount of fuel. The term “off-road competition motorcycle” in this context is also to be understood to include a motorcycle featuring tires for biking on a solid pavement, featuring a spring suspension at the front wheel and rear wheel for competition racing on rough terrain, often termed a “supermoto.”
When a motorcycle is intended to cover long distances without having to stop for refuelling, it is necessary to increase the capacity of the fuel tank. This means that when the saddle tank is full, the force acting vertically on the footprint of the front wheel of the motorcycle is significantly increased. The fuel thus results in an increase in the deadweight of the motorcycle in accordingly significantly increasing the load on the front wheel of the motorcycle, resulting in the motorcycle becoming nose-heavy. The increasing reduction in the level of the fuel in the saddle tank results in a change in the mass distribution of the motorcycle with a significant change in the load on the front wheel during operation of the motorcycle and thus also with a change in the handling response of the motorcycle.
So as to increase the mileage achievable with a single filling of the fuel tank, it is also known to provide auxiliary tanks rear mounted on the motorcycle which together with the saddle tank disposed between seat and handlebars add to the achievable mileage. A motorcycle featuring a saddle tank and an additional tank in the form of a rear-mounted auxiliary tank is known, for example, from U.S. Pat. No. 4,799,569 B1. The motorcycle known from this document comprises a double cradle tubular frame provided with an auxiliary tank at the rear, which thus has no supporting function.
Known from U.S. Pat. No. 5,127,560 is a motorcycle featuring space for accommodating accessory items such as a helmet, instead of a saddle tank as is usual at this location, as well as a rear tank which, however, is not configured self-supporting since it is secured to the rear frame of the motorcycle.
Known from the United Kingdom Patent GB 2 037 678 A is a motorcycle featuring a self-supporting rear tank as the sole tank located below the seat of the motorcycle and extending to the region of a central bridge in the frame of the motorcycle.
U.S. Pat. No. 4,577,719 seems to show a motorcycle fuel system having a main tank disposed between outboard tubular elements of the motorcycle frame with an auxiliary tank below the seat of the motorcycle. In this arrangement, the main tank and the auxiliary tank are fluidly communicated via a connecting conduit.
In addition to the aforementioned double cradle frame, other frame structures for motorcycles are known; for instance, the central tube frame or bridge frame which simultaneously enclose the engine of the motorcycle, or also the tubular trellis frame configured as a framework forming framework bridges on both sides of the engine enclosed thereby. Such a tubular trellis frame features high rigidity due to the framework structure.
Also known from the German motorcycle magazine “MOTORRAD,” No. 13, 2006, at page 16, is an off-road competition motorcycle featuring an internal combustion engine, having one cylinder, and a front wheel as well as a rear wheel, a tubular trellis frame, and a self-supporting fuel tank configured as a rear tank mounted at the rear end of this off-road competition motorcycle. In addition to the self-supporting rear tank, this off-road competition motorcycle features for extra mileage two fuel tanks usually disposed between the seat of the motorcycle and the handlebars, i.e., in a location in front of the seated biker of this known off-road competition motorcycle.
The intention with this off-road competition motorcycle is, no matter whether the fuel tank is full or almost empty, to achieve stable handling over a broad operating range so that the biker can concentrate on the surface ahead, such as surface irregularities to be negotiated without biking being made difficult by the response of the motorcycle being significantly influenced by the fuel level.
In addition, the motorcycle is intended to make it possible that the power furnished by the engine to be communicated also to a loose or slippy surface without the driven rear wheel losing its grip all the time. In addition, the motorcycle is designed to enable the biker to negotiate an obstacle in the form of a stone or other surface irregularity by yanking up the front wheel from the surface in overcoming the obstacle without the front wheel being jolted by the obstacle, ruining the smooth handling of the motorcycle and introducing unsteadiness into the chassis of the motorcycle.
When the off-road competition motorcycle then features a front tank mounted between the biker and handlebars in the form of a saddle tank or the like, this results in a nose-heavy configuration when the fuel tank is full which makes it difficult to yank up the front wheel from the surface. When such an off-road competition motorcycle is negotiating a downhill loose surface, the braking force communicated by the front wheel is diminished because of the front wheel almost instantly losing grip and resulting in skidding and toppling of the motorcycle. It is thus important to communicate the corresponding braking power with the rear wheel which in this context, however, because of the fuel in the saddle tank being sloshed forward downhill is relieved of load in thus reducing the force normal to the rear wheel.
With the foregoing summaries as background, the object of the present invention is thus to sophisticate the known off-road competition motorcycle to avoid the aforementioned disadvantages. To achieve the aforementioned object in avoiding the cited disadvantages, the present disclosure provides for an off-road competition motorcycle having the features described herein after.